Write-Up: Flushing Radiator Coolant

This has got to be a dumb question but, the radiator cap does come off, right? Mine ain't budging.

Is it the original cap? Mine was a bitch to take off too before I changed it. I had literally put all my body weight on it as I rotated it.

It's like a child safety lighter - you have to know how it comes off. Push down and twist harder when you get to the first stop. It will rotate once more and then come off. Make sure the coolant isn't hot!

Thanks, got it off! Hardest radiator cap to remove ever! I had to push down so hard I thought I might damage the radiator, or at least a bracket. And why'd they have to recess the cap so much?

So far I've only got a gallon and a third of antifreeze into the radiator, and a little when into the overflow container. That doesn't sound like enough.

I can't remember if I was supposed to put the RMI in first or not. Does it make any difference?

Jack the R wrote:

Thanks, got it off! Hardest radiator cap to remove ever! I had to push down so hard I thought I might damage the radiator, or at least a bracket. And why'd they have to recess the cap so much?

So far I've only got a gallon and a third of antifreeze into the radiator, and a little when into the overflow container. That doesn't sound like enough.

I can't remember if I was supposed to put the RMI in first or not. Does it make any difference?

Makes no difference, remember you just need a pint. After a few thousand miles pull off the cap and you will see the crud that has settled. Scoop it out and check again later. I would drain the radiator 1 year from now.

Settled in the overflow container?

Jack the R wrote:

Settled in the overflow container?

Under the radiator cap.

Didn't expect it to float.

Some debris will collect inside and stick to the bottom of the cap. You should have noticed some on yours?

AA wrote:

Some debris will collect inside and stick to the bottom of the cap. You should have noticed some on yours?

Clean as a whistle.

Not sure why you are using the RMI-25 if it's not dirty. Is your cooling system performance causing concern? Drain or siphon the old coolant out, replace with new DexCool. Or take to a shop and have it flushed. Costs about $60.

you can leave in a small amount of RMI-25 and it will maintain a clean system. I have it in the Riv, my DD and the '54 MG. Any time we've ever opened up cooling passages they are spotless clean. And you should change some of your fluid occasionally anyhow. I do that every other year, drain and refill the radiator in all my vehicles. Other than bad intake gaskets on the 3800 (I blame plastic intake gaskets) I've never had a problem coolant related.

AA - I'm mindlessly following Deekster's advice on pg 2.

I didn't consider the possibility that it would be too clean for RMI. I don't see any dirt, nor am I having cooling problems.

Deek - How small is small?

I don't think it can be "too clean" for RMI-25, and I don't think using too much can hurt anything. I was just pointing out that if your system is clean, it means your coolant isn't in too bad of shape. Why buy an extra product if all you need is to flush the coolant?

You are still running DexCool, right?

I forget the exact amounts, but I think for "mainenance" you just add like 2 oz to the system.

AA wrote:

I don't think it can be "too clean" for RMI-25, and I don't think using too much can hurt anything. I was just pointing out that if your system is clean, it means your coolant isn't in too bad of shape. Why buy an extra product if all you need is to flush the coolant?

You are still running DexCool, right?

I'm using the RMI instead of flushing the coolant. I've got dogs, I've got to minimize the amount of antifreeze lost.

At some point you're going to need to replace that Dexcool. Even the RMI has a lifespan, and if the coolant has exceeded its life, it will likely contaminate the RMI, reducing it's effectiveness. Just my opinion. FYI, I removed almost all of my coolant out the top using a hand pump into gallon jugs, if that gives you any ideas.

In a year I'll take it to a mechanic and have it all replaced again. At least I got the radiator hoses changed this time. I'm peeved that the heater hoses turned out to be so hard to change though (I didn't try). I wonder if I really accomplished anything at all.

The radiator replacement I have planned should be a lot of fun. I'm just going to cut both hoses, rip the unit out, and replace all.

AA wrote:

The radiator replacement I have planned should be a lot of fun. I'm just going to cut both hoses, rip the unit out, and replace all.

Simple job, 2 hrs max.

AA wrote:

The radiator replacement I have planned should be a lot of fun. I'm just going to cut both hoses, rip the unit out, and replace all.

double tap

AA wrote:

The radiator replacement I have planned should be a lot of fun. I'm just going to cut both hoses, rip the unit out, and replace all.

When I get rich I'll put in a new performance built engine and change the heater hoses then

I ran through Karma's instructions on pg 2, but I never did get any sputtering. I wonder if it's because I topped the radiator off over days? I only got a steady trickle of fluid, the two times I opened the little valve.

Maybe you don't have any air in the system?

Here's hoping. That wouldn't normally be the case though, would it?